DPReview TV: Photo lingo 101 - a guide to common photographic terms

It's back to basics in this week's episode as Chris and Jordan break down some common photographic terms that might not be familiar to newer photographers. Learn all about IBIS, BSI and CIPA, as well as a, shall we say, 'creative' origin story for the word 'bokeh.'

Comments

Sunstars and diffraction. Lately, I have been bracketing f-stop in some situations. Stacking an f/22 with an f/8 or lower shot and brushing in the f/22 stars. Best of both worlds. Works quite well, especially if your PP SW can align handheld shots. Not exactly a beginner thing, that would be bok, eh?

Instantaneous DR of the human eye is less than 13 EV (aka, 13 stops) -- in other words, less than any Sony E body since the original A7! Smaller pixels (typically on MFT and smaller sensors) still struggle, with pixels unable to hold enough charge to distinguish even 10 EV. However, the human eye is very good at dynamically adjusting as you scan a scene, so you see a wider DR over a short period. Cameras can use a similar trick: shoot multiple images and align and combine them to extend DR, as many cell phones now do.

In any case, the scene DR range instantaneously perceptible to a human in the EVF is now usually GREATER than for an OVF. Why? Well, an OLED EVF might only be able to display 10 EV directly -- a JPEG encodes even less -- but the camera's processing for EVF/JPEG can perform TONE MAPPING that takes 13+ EV into a detailed image with a smaller contrast range.

That's not the point of high dynamic range. You can't tell the difference between 48mp and 2mp with most viewing surfaces/distances but that doesn't mean you want to lose that latitude in mastering the final image.

Also, much if the art of photography is not about capturing what the human eye sees. There is an editorial component to tone mapping hdr to an ldr image.

Although since most OLED EVFs I have used have poor colour accuracy and most LCDs EVFs have appalling dynamic range (IIRC one very commonly used Epson one was 240:1) they still have some work to do.

Of course using a transparent RGB OLED (which have been around for 5+ years) as an overlay in an OVF viewfinder (in place of the transparent monochrome LCDs they tend to use now) would be really interesting...

The dynamic range of the human eye is essentially infinite because we have volitional control of our bodies and are toolmaking primates, if a shadow in the forest is too dark to see into we walk over to it and by the time we get there the eye’s f/stop has opened enough to see clearly. Darker still: flashlights or fire. Too bright: the design of our elbows allows us to shade our eyes with our hand, if that fails we have smoked glass, pinholes, and filters.

Speaking of outdated terms “EV” comes from a German exposure system that was invented in the 1950s and hasn’t been used in decades. Can you name one camera made in the last 20 years that uses the EV system? So how about we stop using it too.

The "less than 13 EV" instantaneously seen by the human eye was initially my own empirical measurement inspired by seeing things in the EVF of my Sony A7 that I couldn't see directly... and then I looked-up numbers. Most sources I found pegged instantaneous DR at no more than 9-10 EV, which is not coincidentally roughly what JPEG is designed to represent. Probably more correct is https://en.wikipedia.org/wiki/Human_eye#Dynamic_range quoting 6.5 EV as the "static contrast ratio" (instantaneous DR), with up to 46.5 EV DR if we allow full adaptation (which takes about half an hour -- or a pirate's eye patch). However, some adaptation occurs very quickly as the eye scans a scene, and this seems to be why you get ranges like the 10-14 EV that Cambridge in colour quotes. The Wolfcrow site (top Google hit) seems to claim 20 or even 30 EV, but even it does say "at any given time" it's just 10 EV.

I still use Ev quite a bit and know people who do. It makes thinking about stuff in advance much simpler (e.g. indoors maybe Ev 6, so might want a lens X fast...), or working out the light level people were shooting at from the exposure info and if the image looks under/over exposed.

@ phil from Seattle: Could you please explain, since this is a well known strategy to benefit from the full dynamic range of the sensor. It is a kind of "exposure to the right" strategy for very wide dynamic range scenes.

It's all approximations to what I discussed in my 2015 Electronic Imaging paper, slides at http://aggregate.org/DIT/ei20150210.pdf . Basically, sensors don't really have variable quantum efficiency, so ISO changes are implemented by either analog or digital signal amplification (gain). Analog amplification (commonly implemented in camera ISO settings) shifts the noise floor up and saturates highlights; digital amplification (usually of a raw in post) can do a bit better in that highlights don't need to clip, while noise is similar. Basically you are trying to expose to maximize the information content of the raw image....

Assuming there were no lowlights crushed out when you underexposed or highlights clipped when you raised it 5 EVs, then no, you wouldn't lose anything. Kind of a big if, though. And if you have a scene that fits in the middle, what's the point? Honestly, I think you are better off bracketing exposures and HDRing it. But whatever works for you.

Underexposing helps preserve highlights, but there are no true ISO invariant sensors and all have less noise at higher ISOs, just some have small amounts of noise so you don't care as much. Of course as you can't see the image in the EVF (being somewhat black) you don't know if you got the shot or something went wrong... Swings and Roundabouts.(BTW users of Canon sensors without on-chip ADC - still pretty ISO invariant from 800 and up...)

@ phil from seattle: Describing a scenario where iso invariant exposure strategy doesn't matter and then concluding it is is a waste, is like shooting all day in bright sunlight and say that high ISO is never helpful ... :-)

Oh no... ok. Here goes. A "Camera" is a thing that we carry in our pockets, and it let's us text, make calls, organize our calendars, play games, browse the web, and keep up with our social media game, and sometimes it let's us take pictures. :)

A camera is a device that takes pictures and is usually included in the thing that we carry in our pockets, that let's us text, make calls, organize our calendars, play games, browse the web, and keep up with our social media game, and sometimes it let's us take pictures. :)

It's a great video for beginners, but too much information in it for an absolute beginner.Perhaps a shorter list (like 5 items) and a shorter series of videos (5 to 7 minutes each) would be more effective than a 17-minute packed one.After all, this is for the very beginner.

Yes of course, for the other question regarding more advanced concepts.There is always plenty of room for advanced concepts, especially when it comes to light.I'll share this video (link) with my photography group, which has well over 3,000 members.

The DPR community can be a tough crowd, and I guess a lot of people who don't need this video are going to complain about it, but even though I didn't learn anything new, I enjoyed it a lot. Thumbs up from me!

Fly yes I find it genuinely distressing that they have made another video and I don't want to be aware of it. The good news is Ive worked it out, you go in settings and theres a box to block out what you don't want in your feed, so adding 'dpreview TV, video' stops them appearing which is a real joy. Im thinking of adding things like 'Sony' and 'drone' to create a really good feed.Franz, not sure where page 9 is, but Ive worked something out thanks

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